1. Field of the Invention
The present invention relates to a display control apparatus for gesture operation input onto a touch panel and a control method thereof.
2. Description of the Related Art
In recent years, digital devices including a touch panel in a display unit, and enabling a user to perform an intuitive operation have appeared on the market. In these devices, it is possible not only to execute a function with a button icon placed on a display screen constituted by a touch panel, but also to call the function by performing gesture recognition.
In invoking a function by the gesture recognition, if an input trajectory on the touch panel matches a predetermined trajectory pattern, the function assigned in advance to the trajectory pattern will be invoked. Various functions can be assigned to the trajectory patterns, and a user can also assign arbitrary functions thereto.
When utilizing a function invocation by such the gesture recognition, the user may in some cases be aware that the user is doing wrong gesture operation halfway through dragging for gesture (hereinafter, may be sometimes referred to as gesture operation). For this reason, a technique for canceling a function invocation by the gesture recognition during gesture operation in progress is required.
For example, Japanese Patent Application Laid-Open No. 08-016314 discusses a method for canceling a function invocation by the gesture recognition, if gesture cancellation timeout period is exceeded while staying standstill halfway through a stroke by dragging, or a stroke is too large. Additionally, there is discussed a method for canceling a function invocation by the gesture recognition if an input from another input apparatus is performed while the gesture action is in progress.
However, according to a method discussed in Japanese Patent Application Laid-Open No. 08-016314, the gesture recognition is executed only after a user has performed the gesture operation, and released the finger from the touch panel. For this reason, the user cannot confirm halfway through the gesture operation how the gesture operation performed until present time has been recognized by the apparatus, and cannot find what functions will be invoked before the user leaves the finger from the touch panel.
For this reason, there is a problem in that, even when a pattern, which may invoke an unintended function, is erroneously input, the user cannot aware of it, accordingly cannot cancel it. As a result, an unintended function may be eventually executed.